A protocol chip stores requests from a computer in a port queue, on the basis of an index indicating a slot of the port queue which allows subsequent storing. MPs each hold a CI of the slot having undergone a preceding search of the port queue by the MP, search this port queue from the slot that the pointer indicates, search for a request addressed to a logical device to which the MP corresponds, and store this request in a virtual queue corresponding to the logical device, to process the request.